Lathe for relieving taps



2 Sheets'-Sheet 1.

W. A. ROBERTSON.

LATHE FOR RELIEVING TAPS.

I (No Model.)

Patented Jun 19, 18.94.

( NoModel.) 2 Sh ets--Sheet 2. y W. A. ROBERTSON.

LATHE FOR RELIEVING TAPS.

No. 521,510. Patented June 19,1894.

'1'"! NATIONAL Lmloamwmma comum'.

wnsamm'on. 04 c.

UNITED STATES ATENT FFIJCE;

WILLIAM A. ROBERTSON, OF CEDAR RAPIDS, IOW'A.

LATHE FOR RELIEVING TAPS SPECIFICATION forming part ofLetters Patent No. 521,510, dated June 19,1894.

Application filed March 13, 1894.- Serial No.603,402. (No'modeld To all whom it mag concern.-

Be it'known that I, WILLIAM A. ROBERT- SON, acitizen ofthe United States, residing at Cedar Rapids, in the county of Linn and State of Iowa, have invented certain new and useful Improvements in Lathes for Relieving Taps; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

. This invention relates to lathes'for turning 1rregular forms, and more particularly metal turningv lathes, with more special-reference to the work of relieving taps. Though the mechanism iscapable of being used for the production of many varieties of irregularforms, The particular mechanism by which this re-. sult is accomplished will be hereinafter fully described and claimed, reference being had 1 to the accompanying drawings, in which-=- Figurel is a plan View of a device embodying my inventionas'applied to an: ordinary iron turninglathe.- Fig. 2, Sheet 2, is an endv elevation as seen from the: tail-stock end of the lathe, the lathe bed' being in section. Fig. 3, is a similar fragmentary view'from the opposite side of the operative parts there shown; Fig. 4, is an elevation of a face-plate with a heart-form attached; thereto. Fig. 5, isa'similar View showing a 'circular'form attached to a face-plate eccentrically. Fig. 6, is a transverse section of one of the bearings for the square bar carrying the levers hereinafter to be described.

Similar letters of reference indicate corresponding. parts.

Referring to the drawings, A designates the head-block of an ordinary lathe; B thebed; C the tail-stock; and D the tool-carriage. These are of the usual construction andneed not be particularly described. The face-plate E does not differ especially fromthose in commen use, except as it is provided with suitable holes for the attachment of cams or forms F,-which will be hereinafter more fully described.

The apparatus which forms the subject of this invention is described as follows: To the ways of the lathe are connected bearingblocks G G, which are provided with suitable notches on the under side, to engage with said ways, and are connected theretob'y clampbars G G, bolted tothe bearing-blocks'b-y suitable: cap-screws g g. y In the-upwardly extending portions of these bearing-blocksat the back side of the lathe are mounted re'voiluble sleeves h, which are'providedwith'a square-central hole, to admit, with a sliding fit, the square bar H. In thecase of lathes in ordinary use, this construction issuitable and necessary; but where the device is applied to 1 new lathes, the latter may be provided at the head and tail-stock, with aprojecting lug C, which is siniilarly'provided with a sleeve; to receive the bar. In this case the bearingblocks' may be dispensed with altogether, or one or more of them may be used intermediateof the head and tail-stock, and thus serve as a'steady-rest for the bar;

The device is more specially applicable to :lathes provided with acompound tool-slide D, since'this construction admits ofoone por tion of the tool-slide being used with its reg ular screw feed, while in the other'portio-n the screw-feed may be'disconnected, :asby" the use of the commonsplit nut, or by sim-' ply loosening up .the crankD". The back end of the disconnected part of the slide should be provided with lugs D. Between these lugs is neatly fitted a bar L, which ex tends backwardly, and connects with a short crank arm K, mounted to slide freely on the bar I-I. Near the face-plate isrfastened to the bar a longer upwardly extending. crank arm I, provided with aflange traveler J. The location of this traveler may be changed by means of holes M, andthe movement of the carriage varied accordingly, as will hereinafter more'clearly appear. On the same bar, between the face-plate and the head-block, is mounted another crank arm or leverM, which is provided with a spring N, connect ing it with a transverse bar O,connected-with the lathe bed by a clamp bar 0, the lower end of the spring engagingwith an eye n. Under this leverMismounted an adjustable post P, the lower end of whichis threaded and provided with suitable nuts p p. The

action of this-spring, as will be seen, tends to throw the crank arm I inwardly, while the post serves to limit such inward movement IQO of the arm, thus preventing the traveler J from moving so far inwardly toward the center of the face-plate as to catch on the cams and interfere with the action of the machine.

The device is shown as in use in connection with a tap mounted between the centers of the lathe in the usual way, the purpose in this case being simply to relieve the tap after having been cut and fluted in the usual way. The tap shown has four flutes, and corresponding thereto the faceplate is provided with four camsF F. It is to be understood, however, that any number of cams may be used that may be desired, to correspond with any desired number of flutes of, a tap, or the corresponding parts of any other piece of work. For this purpose it is but necessary to provide a suitable number of holes in the face-plate e e, and make the cams of suitable length. It will be seen in Fig. 1 that the cams are separated a little distance from the face-plate by washers or thimbles f, thus leaving a space between the cams and the faceplate for the inner flange of the traveler J. These cams are made adjustable by means of a slotf", through which passes a tightening screwf. The other end of the cam is pivotally secured to the face-plate by a screw f.

The operation of the device will now-be readily understood. As the face -plate revolves, the arm I is carried a limited distance back and forth by the cams F F, or more strictly speaking, is carried outwardly by said cams, and is moved inwardly through the action of the spring N, a reciprocating motion being thereby given to the toolslide D. As these cams coincide with the threaded portions of the tap, it will be seen that the thread tool, which barely touches the tap at its (the taps) cutting edge, is drawn inwardlya slight distance as the tap revolves, thus relieving the tap at all of its four sides. It is to be understood that this work is done after the tap is cut and fluted, consequently the tap being adjusted with proper relation to the cams, the relieving thereof is done with perfect accuracy. As the tool carriage moves, following the thread on the tap, a crank arm K slides along on the bar coincidently with the movement of the carriage. In practice it is found that ordinarily this is done without any cramping on the part of the arm K, since there is comparatively little side pressure on the tool, and this, with no other connection of the arm than a snug fit of the connecting barL in the lugs D. Where considerable side pressure is brought to bear upon the tool, however, the bar L may be steadied near its connection with the arm K by suitable guidesl 1.

It is to beunderstood that I do not consider that the forms shown in Figs. 4 and 5 will be duplicated in the work, these being shown simply as illustrative of other uses to which the device may be applied. As the arm I moves in the arc of a circle on the bar II, it is, of course, impossible to exactly reproduce in the work the same form as that attached to the faceplate. In practice I mount on a mandrel a form of the exact shape desired in the work, cause it to travel 1n connection with the traveler .I, and by means of a suitable style, or other marker, trace on the face-plate the form of the desired cam to be attached thereto, this form being made and applied to the face-plate, the original cam or form is of course, exactly reproduced.

In Fig. 6 the particular construction of the sleeve his shown. This is provided with a flange, integral with the sleeve at one end, and at the other end the sleeve is provided with a ring 72.. The convenience of this device will be readily seen. becomes possible to completely finish a tap without any hand labor. The tap 1s turned on a lathe in the ordinary way; then taken to the milling machine and fluted; then brought back to the lathe and relieved, when it is ready to be tempered.

Having thus described my invention, I claim- 1. The combination with a lathe substantially as described of cams mounted on its face -plate and separated a short distance therefrom by intermediate Washers or thimbles, a flange traveler mounted on an upwardly extending arm, connected with arectangular rock-shaft, suitable bearings for said rockshaft, a crank arm mounted to slide freely on said rock-shaft, and a. bar connecting said crank with the tool-slide, and means for holding said traveler in contact with the cams, substantially as and for the purpose set forth.

2. In a lathe the combination with its faceplate of adjustable cams corresponding in number to the sides of the work designed to be turned, a crank arm provided with a suitable traveler adapted to ride on the outer faces of said cams, means for retaining the same in contact with said cam surfaces, a rock-shaft on which said arm is mounted, a crank thereon and a connection of said crank with the tool-slide, substantially as and for the purpose set forth.

3. The combination with a lathe substantially as described of one or more cams mounted on the face-plate, a rock-shaft, bearing blocks adapted to retain said rock-shaft, a crank arm or lever, with a traveler connected therewith, adapted to ride on the said cams, a crank connection of said rock-shaft with the tool-slide, a spring connected with an arm extending from said rock-shaft to draw the traveler into contact with the cams, and a stop to limit the inward throw of said traveler.

4.. In a lathe the combination of afaceplate I By this means it v 5. In a lathe the combination with the face In testimony whereof Iaffix my signature in plate provided with one or more cams of the presence of two witnesses. rock-shaft H, the traveler J and its arm I connected with said rock-shaft, crank K adapted WILLIAM. ROBERTSON 5 to slide on said rock-shaft, connecting bar L, Witnesses:

lever M, spring N, and adjustable post P, sub- GIRVIN HALEY,

stantially as and for the purpose set forth. 'L. M. MARTINEK. 

